There are countless situations where a gear, bearing, joint and the like must rotate about a shaft under heavy radial loads and require anti-friction bearings, particularly needle bearings, in between the rotating member and the shaft. While needle bearings can be inserted into a conventional anti-friction bearing retainer which is secured within the bore or hub of the rotating member, it is common practice for the needle bearings to be simply inserted into the hub of the rotating member and the rotating member slipped over the shaft. The hub or bore is liberally greased and the needle bearings, once inserted into the bore, are maintained in proper position and attitudinal alignment within the bore by the grease, the grease also providing lubrication for the bearings. The rotating member with needle bearings packed in its hub by grease is usually pushed onto the shaft by the use of a mandrel.
The mandrel concept is also used in initially packing the needle bearings into the hub of the gear or rotating member after which the gear is shipped (sometimes with a pilot or dummy shaft within its bore) to the site where final application of the gear to the shaft is made. Essentially packing the bearings into the gear's hub is achieved by the use of a recover block having a bore extending therethrough and a bearing slot in communication with the bore through which the bearings are fed. The diameter of the bore in the recover block is equal to the diameter of the bore of the gear member. A mandrel in the form of a stepped shaft having a first diameter portion approximately equal in diameter to the shaft on which the gear member is to be applied and a second diameter portion having a diameter greater than the first diameter portion but less than the diameter of the receiver block's bore, cooperates with the recover block to collect the needle bearings. The length of the first and second portions of the stepped shaft are at least equal to the length of the bore in the recover block which in turn is at least equal in length to the bore in the gear member.
The gear member with grease liberally applied within its bore is brought, by means of a transfer station, into concentric alignment with the bore of the recover block and closely adjacent to one axial end of the recover block. The first diameter portion of the mandrel is inserted into the recover block from the opposite axial end in concentric relationship with the recover block's bore. Needle bearings are then fed by gravity through the bearing slot in the recover block into the annular space between first diameter shaft portion and the bore of the recover block. After the annular space is filled with needle bearings, the second shaft diameter portion pushes the needle bearings out of the recover block and into the hub of the gear. The bearings are retained by the grease in the hub of the gear and the first diameter portion retracted from the gear member and again positioned in concentric relationship within the recover block.
The gear is then rolled on the transfer station to another position whereat a pilot shaft is inserted into the member from the opposite end and laterally moved to determine if all the needle bearings are positioned within the bore or hub of the gear. The pilot shaft can then be left in the gear for transporting purposes or removed, in which event, the grease itself acts as a packing to maintain the bearings within the bore of the gear during transit.
The feed mechanism for loading the needle bearings into the recover block in the annular bearing space comprised a track which holds a vertical column of needle bearings positioned over and in registry with the bearing slot in the recover block. The weight of the needle bearings in the column provided the force to load the needles into the annular bearing space. To provide some means of controlling the vertical drop of the needle bearings, the track was constructed to comprise horizontal passage segments perpendicular to vertical passage segments so that the actual downward force exerted on the lowest bearing in any vertical segment of the trace was attributed only to the weight of the needle bearings in that vertical segment. By constructing the track in such a manner, the flow of needle bearings into the annular bearing space proceeded in a controlled manner and was enhanced by oscillating the mandrel to result in a fairly reliable arrangement for loading the needle bearings into the annular bearing space.
While the arrangement described above was satisfactory, the cycle time of the assembly was limited by the time it took the needles to drop by gravity to fill the annular bearing space. In addition, it was possible for the bearings to assume a cocked alignment within the annular bearing space thus preventing the bearings from completely filling such space and resulting in a defective assembly.